Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.
-
Upload
april-baldwin -
Category
Documents
-
view
216 -
download
1
Transcript of Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.
![Page 1: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/1.jpg)
Principle of Index-Velocity Method and its Application
Randy Marsden
Teledyne RD Instruments
![Page 2: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/2.jpg)
Summary
• Principles
• Example
• Practical Procedures
![Page 3: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/3.jpg)
Part 1:
Index-Velocity Method: Principles
![Page 4: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/4.jpg)
Why is an Index-Velocity method needed?
• Need: Continuous discharge measurement for open channels where simple methods like stage-discharge relationship do not give reliable results
• Examples:– Tidal rivers– Backwater conditions– Canals or rivers with control structures
![Page 5: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/5.jpg)
• Establish a relationship between channel mean velocity and an Index-Velocity
• Index-velocity is a velocity measured at a local area (sampling volume) on the cross-section.
What is Index-Velocity Method?
![Page 6: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/6.jpg)
• Developed by USGS in 1972• Used in U.S., China, France, Great Britain,
Japan, Canada, Mexico…….
• Instruments for Index-velocity Horizontal ADCP, i.e., ChannelMaster Acoustic travel time instruments
Index Velocity Method
![Page 7: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/7.jpg)
In practice, three types of local velocity can be used as Index-velocity
• Horizontally averaged velocity at a depth
• Depth averaged velocity in a vertical
• Point velocity
Three Types of Index-Velocity
![Page 8: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/8.jpg)
Point velocity
Depth averaged velocity
Horizontally averaged velocity
![Page 9: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/9.jpg)
• H-ADCP (horizontally-looking) or travel time system. – Example: ChannelMaster
• Bottom-mounted ADCP: looking-up– Example: ADFM
• Point current meter for point velocity– Example: Marsh Mcbirney EM meter
How to measure Index-velocity?
![Page 10: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/10.jpg)
Fundamentals
Discharge equation:
Q = A Vmean
Q = Discharge
A = Cross-section area
Vmean = Channel mean velocity
![Page 11: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/11.jpg)
Cross-section area is a function of stage
A = f (H)
H = stage
A site may already have a table or curve for the stage-area relationship
Index Velocity Method - Area
![Page 12: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/12.jpg)
Mean Velocity
• Vmean = k * Vindex
• k may depend on depth
– Usually not the case on irrigation canals since depth does not vary as much as natural streams
![Page 13: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/13.jpg)
0
5
10
15
20
25
0 50 100 150 200 250 300 350 400
Station (feet)
Sta
ge
(fe
et)
Surveyed Standard
Channel needs to be surveyed for a selected “standard” cross-section to compute channel areas for a range of stages: stage-area ratingMan-made channels may use known dimensions.
Determining Cross-section Area
![Page 14: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/14.jpg)
Channel area is always calculated at the “Standard” Cross-section
• H-ADCP not necessarily mounted at the “Standard” Cross-section location but it should not be too far away
Which cross-section?
![Page 15: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/15.jpg)
A gauging station
1 = standard cross-section2 = wading measurement section3 = bridge measurement section
• Q1 = Q2 = Q3• Area is always computed at location 1!
1 2 3
GageCM
![Page 16: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/16.jpg)
Stage-Area Rating
In many cases, stage-area rating may be expressed as:
A = a1 + a2 H + a3 H2
a1, a2, a3 = coefficients H = Stage
![Page 17: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/17.jpg)
Rating curve = regression equation
One parameter regression
V = f (Vi )
Two parameter regression
V = f (Vi , H)
Index-Velocity Rating
![Page 18: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/18.jpg)
A general, two parameter (Index-velocity and stage) linear regression:
Vmean = b1 + (b2+b3 H) VIndex
VI = Index-velocity
b1, b2, b3 = regression coefficients
Need at least six measurements at different velocities and depths to
due full regression
Linear Regression
![Page 19: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/19.jpg)
One parameter linear regression
If b3 = 0:
Vmean = b1 + b2 VIndex
That is, channel mean velocity is a linear function of
Index-velocity.
Need at least four measurements at different velocities
and depths
![Page 20: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/20.jpg)
Simple Linear
• If have only one or two measurements
Vmean = b2 VIndex
• Found to work well in canals and many rivers
when there is downstream control
![Page 21: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/21.jpg)
Rating Development
Step One: Field data
collection
• Use ChannelMaster to
measure index velocity
• Use Rio Grande or
StreamPro to measure Q
and A
![Page 22: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/22.jpg)
Rating Development
Step 2: Regression analysis
• Data collection need to be
conducted over a range of stage
or discharge to obtain a series of
data for Index-velocity and
channel velocity. Regression
analysis using a least-square
method to obtain Index-velocity
rating curve or equation.
• Same for area.
X Variable 1 Line Fit Plot
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2
CM VELX
ME
AN
CH
AN
NE
L V
EL
Y
Predicted Y
![Page 23: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/23.jpg)
Rating Results
• Q = Vmean(Vindex, H) * A(H)
• Simplest Case: trapezoidal canal
• Q = k * Vindex * (a2H + a3H2)
• a2 is width of bottom of canal
• a3 is slope of canal banks
![Page 24: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/24.jpg)
Accuracy
• Accuracy depends on quality of rating data.– How accurate and reliable is measured index
velocity?– How well does index velocity represent the
mean velocity – how good is k?– How accurate and reproducible is measured
discharge and area?
![Page 25: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/25.jpg)
Canal 18
• Take data with ChannelMaster1200 kHz20 each 0.5 meter cells30 pings, 0.5 sec/ping
• Result for 35 minutes of dataVavg = 0.329 m/s ± 2.3%
![Page 26: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/26.jpg)
Canal 18 Continued
• Rio Grande Discharge data
– 17 discharge measurements
– Vmean = 0.283 m/s ± 1.4%
– Amean = 41.06 m2 ± 1.7%
– Qmean = 11.63 m3/s ± 1.9%
![Page 27: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/27.jpg)
Canal 18 Rating
• b2 = 0.86 ± 2.7%
• a2 = 8.01m ± 1%
• a3 = 2.87 ± 1%
• Q = (b2*VIndex)*(a2* H + a3 *H2) ± 3%
• This is for each 30 second discharge measurement.
![Page 28: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/28.jpg)
Canal 18
• Since the discharge measurement noise is primarily random it could be reduced by doing more pings during the 30 seconds. By reducing the ping time to 0.1 seconds, and pinging for 20 out of 30 seconds, the noise of Vindex would be reduced to ± 1.3% and the uncertainty of the discharge to ± 2.0%.
![Page 29: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/29.jpg)
How is this possible?
• The ChannelMaster and the Rio Grande both use BroadBand ADCP technology which gives:
• Low noise velocity measurement in short averaging times –
• a narrowband ADCP needs 50 times as many pings to reach the same precision for the same cell size.
![Page 30: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/30.jpg)
BroadBand ADCP cont.
• BroadBand ADCPs can use smaller cells to measure the water
• For the ChannelMaster this means that there are more velocity measurements across the canal and they are closer to each bank – better accuracy for Vindex.
• For the Rio Grande this means more vertical depth cells with less estimated flow – better accuracy for Vmean.
![Page 31: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/31.jpg)
![Page 32: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/32.jpg)
![Page 33: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/33.jpg)
Other reasons for BroadBand
• Less pings = less powerSmaller batteriesSmaller solar panels
• Pick the best number of cells and cell size for each siteCover more of flowReduce uncertainty
![Page 34: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/34.jpg)
Part 2:
Application Example
![Page 35: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/35.jpg)
Index-Velocity Rating Development at Imperial Irrigation District, California,
December, 2003
![Page 36: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/36.jpg)
Imperial Irrigation District CaliforniaTrifolium 13 Check structure
600 kHz CM H-ADCPmounted upstream the check structure
![Page 37: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/37.jpg)
Acousti cBeams
Mean FlowDi rectionX
Y
Z
Y
Cel l 1 Cel l jH-ADCP
H-ADCP
H0
0
CanalBank Canal
Bank
Canal Bottom
Water Surface
Sketch for ChannelMaster H-ADCP set-up
![Page 38: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/38.jpg)
StreamPro ADCP used for discharge measurement
![Page 39: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/39.jpg)
H-ADCP Parameter settings:
Cell size: 0.5 meterNumber of cells: 20Blank distance: 0.5 meterAveraging Interval: 37.4 secondsSampling Interval: 37.4 seconds
![Page 40: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/40.jpg)
Screenshot from WinRiver software when
playing back a StreamPro data file
![Page 41: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/41.jpg)
Time series of range averaged Vx for Cells 1 through 4 and
water level at the sampling/averaging interval of 37.4 seconds
0
0.1
0.2
0.3
0.4
0.5
0.6
12:00:00 13:12:00 14:24:00 15:36:00 16:48:00
Time
Ve
loc
ity
(m
/s)
0
0.1
0.2
0.3
0.4
0.5
0.6
Wat
er L
evel
(m
)
Velocity Water Level
![Page 42: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/42.jpg)
Organizing Data for Regression Analysis
i
ki
ki
j
jjxkI VV
4 4
1, )(
4
1
5
1
Index-Velocity: calculate average velocity from CM during the time of a StreamPro velocity measurement
k = 1, 2, 3
![Page 43: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/43.jpg)
Stage: Directly from H-ADCP vertical beam
)(]67.0
[ ADCPbottomADCP ZHWZH
A
Imperial Irrigation District Westside Highline CanalBed Geometry
0
1
2
3
4
5
0 3 6 9
Canal Boundary
Channel Master
Water level
compute from shape of canal
Note: H=1.07m, W=3.0 so
A=1.5Z2ADCP+6.21ZADCP +4.93
Cross-section Area
![Page 44: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/44.jpg)
A
QV measuredmean
Canal Mean Velocity:
Get Qmeasured from StreamPro, Rio Grande, or ‘conventional” methods
![Page 45: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/45.jpg)
Partial Data from StreamPro ADCP and ChannelMaster H-ADCP Organized for Index-Velocity Rating Development
StreamPro ADCP Measurement ChannelMaster H-ADCP Measurement
Transect Start Time
Measured Discharge (Qmeasured)
[m3/s]
Canal Mean
Velocity (Vmean)
[m/s]Sample
Start Time
Water Level (H)
[m]
Index-Velocity
(VI)
[m/s]
Cross-Section Area (A)
[m2]
12:44:56 2.482 0.304 12:44:56 0.470 0.351 8.175
12:49:03 2.264 0.280 12:49:18 0.460 0.336 8.098
12:57:01 1.914 0.239 12:57:24 0.453 0.274 8.041
13:01:31 1.391 0.172 13:01:46 0.455 0.199 8.060
13:11:05 0.954 0.120 13:11:07 0.435 0.146 7.909
13:14:41 0.783 0.099 13:14:51 0.425 0.127 7.834
13:21:01 0.574 0.074 13:21:05 0.413 0.088 7.740
13:24:57 0.474 0.061 13:24:49 0.405 0.069 7.684
13:36:20 0.256 0.034 13:36:03 0.385 0.045 7.536
13:40:36 0.247 0.033 13:40:24 0.388 0.045 7.555
![Page 46: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/46.jpg)
Regression equation:
Vmean vs. VI
y = 0.8606x
R2 = 0.995
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.000 0.100 0.200 0.300 0.400 0.500
VI (m/s)
Vm
ean
(m
/s)
2 m range Linear (2 m range)
Imean VV 8606.0
![Page 47: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/47.jpg)
A stage-discharge rating cannot be created at this site
0
0.5
1
1.5
2
2.5
3
3.5
0.300 0.350 0.400 0.450 0.500 0.550
Water Level (m)
Dis
char
ge
(m^
3/s)
![Page 48: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/48.jpg)
Time series of rated discharges by applying the rating to the H-ADCP data and StreamPro ADCP measured
discharges on December 9, 2003
0
0.5
1
1.5
2
2.5
3
3.5
12:00:00 13:12:00 14:24:00 15:36:00 16:48:00
Time
Dis
ch
arg
e (
m3/s
)
SP Rated Q
![Page 49: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/49.jpg)
Rating evaluation
Regression coefficient: R or R2
Standard Error
Used as indication of goodness of fit: closer to 1.00 is a better fit
![Page 50: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/50.jpg)
Part 3
• Procedures and recommendations• Site selection• Mounting depth• Pitch and roll• Mount• Cell size• Selection of the good cells
![Page 51: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/51.jpg)
Site Selection
• Choose site with best aspect ratio
• Aspect ratio is width/center depth
• Do not want beam hitting bottom sooner than necessary
![Page 52: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/52.jpg)
Mounting depth
• Mount at 50-60% of mean low water elevation. This is near the average velocity point of the vertical profile.
• Provides widest range of operation
![Page 53: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/53.jpg)
Pitch and Roll
• Mount with pitch and roll as close to zero as possible– Maximizes useful range– Beams looking at same plane of the water– Requires pitch/roll sensor
• Use the Mount ADCP screen in WinHADCP to assist setting up.
• After maintenance you can be sure that CM is pointed in the same direction to prevent a shift of the rating.
![Page 54: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/54.jpg)
The Mount
• The mount should be:
– Rigid: shaking can introduce unwanted noise– Adjustable: to allow pitch and roll to be set
close to zero– Retractable: to allow routine cleaning– Reset easily: to put ADCP back to original
orientation
![Page 55: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/55.jpg)
Example mounts
![Page 56: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/56.jpg)
Cell size
• Select a good cell size for the application• Compromise between low noise and maximum
profiling range• Large cells have low noise but may limit how close
you can get to the far bank – small cells averaged together have same noise as one large cell of the same width.
• 20 cells is enough for most applications• SDI-12: up to 27 cells for SDI-12 Version 1.2 and
twenty cells for Version 1.3
![Page 57: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/57.jpg)
Selection of good cells
• Do not want to use cells contaminated by far bank.
• Look at intensity and correlation plots do determine maximum useful profiling range
• Intensity appears to show data ok to 8.8 meters
• But we see that that cell ‘looks wrong’
![Page 58: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/58.jpg)
Selection of good cells continued
Correlation data shows that cell at 8.8 meters has correlation contamination and should not be used
![Page 59: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/59.jpg)
?Questions?
![Page 60: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/60.jpg)
![Page 61: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/61.jpg)
LinearCurvilinear Compound
One Parameter Rating Forms
![Page 62: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/62.jpg)
One Parameter Curvilinear Ratings
x
y
Polynomial
y = b + c1x + c2x2 + c3x3...
x
y
Logarithmic
y =c1ln(x) + b
x
y
Exponential
y =c1ebx
Power law
y =c1xb
x
y
![Page 63: Principle of Index-Velocity Method and its Application Randy Marsden Teledyne RD Instruments.](https://reader038.fdocuments.us/reader038/viewer/2022103123/56649d8c5503460f94a73a39/html5/thumbnails/63.jpg)
One Parameter Compound Ratings
A B
Vi
V A
BTransition
A = Linear
B = Linear